This project studies the temperature variation of 'g' and 'A' factors of diluted and undiluted monomeric Copper(II) complexes formed with nitrogenous ligands. In the case of tetrahedral complexes, these variations are noticed only in [(C2H5)4N]2[CwCl4] (A. Bencini, C. Benelli and Gatteschi, Inorg. Chem. 19, 1980, p. 1632). Exchange, dipolar and spin-lattice interactions are main sources of line broadening. The former and the latter can be avoided by working at high frequencies and lower temperatures. The low temperature spectra are not only well resolved but also represent static structures, since all types of molecular and sub-molecular motions will be arrested. Keeping in view the above facts we have chosen four and six co-ordinate Nitrogenous Copper(II) complexes both diluted and undiluted forms to study the dynamic as well as static structural properties. For some of these complexes already X-ray structural studies, electronic spectral studies and EPR studies at 300, 123, and 77 K were carried out. Studies at 4.2 K both at X- and Q-bands are helping us understand the true structural magnetic properties.